Systems Engineering Society of China

The Moon exhibits extreme environmental characteristics such as prolonged day-night cycle, large temperature fluctuations, high vacuum, and intense radiation, significantly limiting the applicability of traditional building thermal engineering and energy design methods in this environment. These environmental characteristics pose severe challenges to the thermal performance of lunar base buildings and the stability and safety of their energy systems. Therefore, this paper explores the key technical challenges and primary solutions in the construction of energy systems for long-term lunar habitats. It proposes that by advancing research on precise prediction technologies for building and equipment loads in lunar bases, key technologies for efficient energy storage and photovoltaic power generation, as well as the construction and optimization of multi-energy synergistic energy systems for lunar bases, the autonomy and reliability of lunar energy systems can be enhanced, thereby ensuring the sustained operation of future lunar bases.

Blades are widely used in the engines of aerospace vehicles, fans of near-space aerostat, and other equipment, and they are the key to completing energy conversion and pressure adjustment of the capsule. Blade tip timing (BTT) is the most cost-efficient approach for the monitoring of blades. The reliability and validity of BTT is mainly investigated through numerical simulation and experimental verification. However, not all researchers are able to carry out the expensive and time-consuming task of rotating the blade test bench and its monitoring systems. Therefore, a good and easily understood simulator is necessary. In this paper, an effective BTT simulation model that is capable of considering various uncertainties such as installation errors, probe accuracy, sampling clock frequency, speed fluctuations, and mistuning is presented. A blade multi-harmonic vibration model is also presented, which is not only easy to implement but also simplifies the solution of dynamic equations. Also, the simulation results show that the proposed model is accurate and consistent with the experimental results. This will help researchers to achieve an improved understanding of BTT and form the basis for conducting research in related areas in a short period of time.

Gas turbine rotor blade cracks are usually caused by high-cycle fatigue. The natural frequency and damping of the blades change as the cracks propagate. Most existing methods detect fatigue cracks by observing the decrease in natural frequency, which may lead to misjudgment. This article proposes a method for diagnosing blade fatigue cracks by combining the indicators of natural frequency decrease and damping ratio increase. Extracting these two parameters using blade tip timing (BTT) data faces challenges such as signal undersampling and errors in identifying the resonance location due to different sensor layouts. This article introduces a method for extracting natural frequency and damping using only two sensors under uniform acceleration (sweep frequency) excitation. For natural frequency extraction, an adaptive window length sparse representation method is proposed, which can adaptively select the spectral window parameters based on the sampled data and effectively reduce leakage by adding weighting factors. For damping extraction, a center-fixed half-power bandwidth method is proposed. This method improves the half-power bandwidth method by locating the resonance center based on the extracted natural frequency, avoiding interference from “dip” data caused by different sensor layouts. Finally, an accelerated fatigue experiment on a blisk verifies the accuracy of the extracted parameters and the sensitivity of the natural frequency and damping indicators to fatigue cracks.

Abstract Aiming at the low operation rate of the firing mechanism of ammunition fuze, robustness analysis and probabilistic design methods were introduced into the fuze design to carry out system simulation research on performance prediction and optimization of the firing mechanism of ammunition fuze. In this paper, the dynamic model of the inertial impact switch of a proximity fuze is established, and the mechanism can be reliably triggered under nominal values by simulation method. Based on the Monte Carlo simulation of dimensional tolerance distribution, the trigger performance is evaluated. The contribution rate of each dimension variable to the target value is obtained by using the optimal Latin hypercube experiment design, and the variable tolerance with greater contribution rate is optimized by Pointer algorithm. After optimization, the range of variable Jdxh_f was optimized from 0.1274 to 0.1666 to 0.1274 to 0.1556. Finally, the optimized results were validated, with a uniform distribution yielding 0.003193517N, a bimodal distribution yielding 0.2230769N, and a normal distribution yielding 0.2778532N. The validation analysis of these results shows that the target value distribution data after optimization meets the design requirements. This study seeks a balance between performance reliability and manufacturing cost, which is of great significance to improve product performance and reduce manufacturing cost.

During object tracking process, if only the first frame is used as the matching template, changes about the target state will often lead to poor tracking results or even tracking failure of the classic Siamese tracker. To deal with this issue, UpdateNet uses the first frame as template, and regularly updates the template with combination of the previous accumulated template and the current predicted template. However, the combining of template tends to bring in background information which may pollute the template representation. For the purpose of obtaining accurate template and timely sensing the change of target, this article introduces the Squeeze-and-Excitation channel attention and selective mechanism to UpdateNet. The channel attention mechanism can sort the template information spliced by channels by adjusting the weight to highlight important information. The confidence score of the tracking predicted result of the Siamese network is used to determine whether the corresponding frame should participate in template accumulation, and a threshold is set to exclude severely contaminated predicted templates. The article also uses a more detailed parameter adjustment method to enable UpdateNet to achieve convergence faster and be more adaptive. We apply the improved UpdateNet into the DaSiamRPN tracker, and evaluations on the VOT2016 and VOT2018 datasets show that our methods can effectively improve the performance of UpdateNet.